Distribution

North America, Europe, Asia.

Discussion

Genera 5, species 14 (4 genera, 6 species in the flora).

In addition to the four genera treated here, one other genus completes the family: Berneuxia Decaisne, with one species in the Sino-Himalayan Mountains. Diapensia lapponica and its sister D. obovata, as a pair, are circumboreal in distribution; all of the other species of the family are narrowly distributed. A phylogenetic analysis based on morphology and molecular data from four genes (K. Rönblom and A. A. Anderberg 2002) indicated that Galax is sister to all other genera; Pyxidanthera is sister to the remaining genera at the next higher node; relationships among Berneuxia, Diapensia, and Shortia are unresolved. In this interpretation, the “inverted-eucamptodromous” venation pattern shared by Diapensia and Pyxidanthera (H. T. Murphy and J. W. Hardin 1976) was perhaps developed in parallel.

Leaves of Diapensia, Galax, and some Shortia species become reddish to purplish or orange-bronze (anthocyanic) in the fall and winter. The colored leaves of Galax are gathered in the fall for the florist trade. Leaves of all genera of Diapensiaceae sequester large amounts of aluminum (L. Schultz, pers. comm.), an unusual characteristic for temperate plants.